Twin-type slewing crane

ABSTRACT

A twin-type slewing crane includes a base rotatably mounted on an upright support which may be positioned, for example, between two holds of a vessel, and driving means for rotating the base about the support. Two upright columns or masts are mounted on the support adjacent opposite ends of a diameter thereof. Each mast is embraced by an annular bearing each of which pivotally mounts a respective jib or boom for swinging movement in a vertical plane, and respective driving means are associated with each annular bearing to swing the associated boom around the axis of the respective mast. A pair of elevating winches are mounted in axial alignment on the base between the masts, and each connected by cables, trained over pulleys mounted on the associated mast, to the respective booms to raise and lower the booms. A pair of winding winches are also mounted in axial alignment on the base and connected by cables, again trained over pulleys mounted on the associated mast and on the outer end of the associated boom, to lifting hooks or the like. Respective clutch means are provided for each pair of winches so that the elevating winches may be interconnected to operate in synchronism and also the winding winches may be interconnected, to operate in synchronism. Such synchronized operation is utilized when the two booms are swung into substantially parallel relation with each other to act as a twin crane in lifting very heavy loads. Certain of the pulleys may be mounted on a member interconnecting the two masts near the upper ends thereof. In a variant embodiment, the booms are raised and lowered by hydraulic actuators which are connected to sources of hydraulic fluid under pressure through valve means which permit independent operation of each hydraulic actuator, in a parallel arrangement, or synchronized operation of the two hydraulic actuators, connected in series relation.

United States Patent ()da et al.

[54] TWIN-TYPE SLEWING CRANE [72] Inventors: Masao Oda; Noriaki Kijima,both of Shimonoseki, Japan I Atitslglltttil Mitsubishi .lukogyoKahushlki Kaisha, Tokyo [22] Filed: Feb. 3, 1971 [21] Appl. No.: 112,282

[30] Foreign Application Priority Data May 15, 1970 Japan ..45/41132[52] US. Cl. ..212/47, 212/3, 212/58, 212/35, 212/69, 214/15 R [51] Int.Cl. ..B63b 27/06 [58] Field of Search ..212/41, 45, 47, 50, 66, 69,212/57,58 R,64, 144,35, 3; 214/14, 15 R [56] References Cited UNITEDSTATES PATENTS 891,796 6/1908 Cooper ..212747 1,439,047 12/1922 Wood etal. ..2l2/l44 X 3,228,534 1/1966 Thaeter et al ..2l2/144 X A twin-typeslewing crane includes a base rotatably mounted on an upright supportwhich may be posi- Aug. 15, 1972 tioned, for example, between two holdsof a vessel, and driving means for rotating the base about the support.Two upright columns or masts are mounted on the support adjacentopposite ends of a diameter thereof. Each mast is embraced by an annularbearing each of which pivotally mounts a respective jib or boom forswinging movement in a vertical plane, and respective driving means areassociated with each annular bearing to swing the associated boom aroundthe axis of the respective mast. A pair of elevating winches are mountedin axial alignment on the base between the masts, and each connected bycables, trained over pulleys mounted on the associated mast, to therespective booms to raise and lower the booms. A pair of winding winchesare also mounted in axial alignment on the base and connected by cables,again trained over pulleys mounted on the associated mast and on theouter end of the associated boom, to lifting hooks or the like.Respective clutch means are provided for each pair of winches so thatthe elevating winches may be interconnected to operate in synchronismand also the winding winches may be interconnected, to operate insynchronism. Such synchronized operation is utilized when the two boomsare swung into substantially parallel relation with each other to act asa twin crane in lifting very heavy loads. Certain of the pulleys may bemounted on a member interconnecting the two masts near the upper endsthereof. In a variant embodiment, the booms are raised and lowered byhydraulic actuators which are connected to sources of hydraulic fluidunder pressure through valve means w lCl'l permit independent operationof each hydraulic actuator, in a parallel arrangement, or synchronizedoperation of the two hydraulic actuators, connected in series relation.

9 Claims, 7 Drawing Figures PATENTEDAUG 1 5 m2 SHEEI 1 BF 3 FIG.!

' INVENTORS MASA 0 00A BY NOPIAK/ OJ/M4 4am 4rfoalers PATENTEDAUB 151972 3,684,104

sum 2 or 3 INVENTOR5 M4540 004 ME/AK/ KAI/A14 H65 zj/zw ,4 TTOAQA/E/iTWIN-TYPE SLEWING CRANE BACKGROUND OF THE INVENTION Prior to thisinvention, it has been the practice to mount two individual cranes on acommon rotatable base so that the cranes may be used singly or incombination depending upon the weight of the cargo to be handled. Whenthe cranes are to be used as a twin crane, the jibs or booms of the twocranes are arranged in parallel relation and operated concurrently,whereby a heavy load may be handled by a force which is twice that ofthe single crane.

Since each of the two individual cranes is provided I with its ownwinding jib and elevating winches, and also with a swivelling winch, thewiring and piping become extremely complicated and maintenance andinspection become inconvenient and time consuming. In addition, themaintenance of synchronism between the individual cranes, which is mostimportant in the conjoint use of the individual cranes as a twin-typeslewing crane, becomes highly complicated and difficult to attain.Therefore, the difficulties involved in conjoint operation of the 'twocranes as a twin crane become an obstacle to efficient operation of suchknown twin-type slewing cranes, and they are accordingly less attractiveindustrially because of the increased costs resulting from suchobstacles.

SUMMARY OF THE INVENTION This invention relates to twin-type slewingcranes and, more particularly, to a twin-type slewing crane free of thedisadvantages of prior art twin-type slewing cranes and with whichsynchronized conjoint operation of two individual cranes, when operatingas a twin crane, can be easily attained and maintained.

In accordance with the invention, a common swivel mount or base isrotatably mounted on a mounting base or support on a water-borne.vessel, and two upright posts or masts are secured to, or integralwith, the common swivel mount to extend upwardly therefrom atdiametrically opposite symmetrical locations. A driving means isprovided to rotate the swivel mount about its support. Near its lowerend, each mast is embraced by an annular bearing which pivotallysupports a respective boom or jib for swinging movement in a verticalplane, and respective driving means are operable to swing each boom orjib about its associated mast.

A pair of hoisting winches are mounted on the common swivel mount andare connected by cables, trained over pulleys, to the hoisting hooks orthe like of each crane, and a pair of jib elevating winches are alsomounted on the common swivel mount and connected by cables, trained overpulleys, to the respective booms or jibs for raising and lowering thesame. The two hoisting winches may be interconnected by suitable clutchmeans for conjoint operation, and the two elevating winches likewise maybe interconnected by clutch means for conjoint operation. Preferably,the two hoisting winches are arranged in axial alignment with eachother, as are also the two hoisting winches. Thus, the individual cranesmay be independently operated both in elevation and in traverse. -Whenan exceptionally heavy load is to be lifted, the two jibs or booms areswung into substantially parallel relation, and the two clutch means areoperated to interconnect the two winding winches and to interconnect thetwo hoisting winches, whereby the two individual cranes are conjointlyoperated as a twin-type crane.

Some of the pulleys associated with the cranes may be mounted on acommon support interconnecting the two masts adjacent their upper ends.Furthermore, in a variation of the invention, the elevating winches maybe replaced by hydraulic actuators each connected between a mast and itsassociated jib or broom to raise and lower the associated jib or boom.These hydraulic actuators are connected, by suitable selecting valves,to sources of hydraulic fluid under pressure, whereby the hydraulicactuators may be operated independently of each other, in parallel, orconjointly with each other, by being connected in series.

An object of the invention is to provide a twin-type slewing crane freeof the disadvantages of the prior art and with which synchronizedoperation of two individual cranes, with maintenance of synchronism, canbe effected easily when the cranes are used as a twin crane.

Another object of the invention isto provide an improved twin-type cranecapable of loading and unloading operations with high efficieney inhandling cargo ranging from a light load to a heavy load.

A further object of the invention is to provide such a twin-type slewingcrane in which the individual cranes are mounted on a common swivel basewhich is rotatably supported on a suitable mounting means.

A further object of the invention is to provide such a twin-type slewingcrane which may be adapted for operation either by mechanical winches orby hydraulic actuators.

For an understanding of the principles of the invention, reference ismade to the following description of typical embodiments thereof asillustrated in the ac companying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a front elevational view of one form of twintype slewing craneembodying the invention and illustrating the cranes as arranged forindividual operation;

FIG 2 is a plan view of the crane shown in FIG. 1;

FIG. 3 is a plan view of the crane shown in FIG. 1 as arranged foroperation as a twin-type slewing crane;

FIG. 4 is an axial sectional view of the lower portion of the craneshown in FIG. 1, illustrating details of the driving arrangements;

' FIG. 5 is a view, similar to FIG. 1, illustrating the crane masts asinterconnected adjacent their upper ends;

FIG. 6 is a front elevation view of a twin-type slewing crane forminganother embodiment of the invention and in which vertical swingingmovement of the booms or jibs is effected by hydraulic actuators; and

FIG. 7 is a hydraulic circuit diagram pertaining to the crane shown inFIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will bedescribed byway of example hereafter with reference to the accompanyingdrawings. Referring first to FIGS. 1 to 4, reference numeral ldesignates a common mount or base which is rotatably mounted on a fixedbase or support 3 of a ship, and has two posts or mast 2, and 2 fixedlymounted thereon or integral therewith. The mounting positions of theposts 2 and 2' are diametrically symmetrical with respect to the centerof mounting base 3. Reference numerals 4 and 4' designate jibs or boomsconnected to the respective posts 2 and 2' for swinging motionthereabout. Elevating switches 5 and 5, for elevating the respectivejibs 4 and 4', two single crane swinging mechanisms 6 and 6' forswinging the respective jibs 4 and 4' and two winding winches 8 and 8'for moving respective weights or hooks 7 and 7 upwardly and downwardly,are mounted on the common mount or base 1. Mounting base or support 3 isfixed on the hull of the ship between two hatches 9 and 9, and has aturntable bearing 10 provided thereon. The structure on and above thecommon swivel base 1 is rotatable as a unit, and a rotation mechanism 1l for twin operation, is mounted within the common base 1. Respectiveannular bearings 12 and 12' embrace posts 2 and 2 for single operation,with the inner race 13 of each bearing 12, 12' being fixed on therespective post 2, 2', while the outer race 14 thereof is integral witha large ring gear 15 meshing with the pinion 16 of the associatedswinging mechanism 6 or 6'. A respective jib-mounting housing 23 issecured to each outer race 14, so that the outer race 14 and theassociated jib are moved as a unit. With such an arrangement, theupsetting moment is taken entirely by the associated post 2 or 2.

The arrangement of the respective winches is as shown in FIG. 2. The twowinding winches 8, 8' and two jib elevating winches 5, 5' are arrangedbetween the posts 2 and 2 in such a manner that the drums of therespective winding winches are axially aligned as are also the drums ofthe respective elevating winches.

I Respective clutches 17, 17 are provided between the winches of eachaxially aligned pair so that two drums may be coupled together forconjoint synchronized operation.

The wires or cables of winding winches 8, 8' extend into the interior ofthe associated posts or mast 2, 2' over pulleys 18, 18', at intermediateportions of the posts, and pulleys 19, 19', within the posts, and reachpulleys 21, 21', at the tip ends of the respective jibs, over pulleys20, 20' at the top ends of the associated posts, to move the associatedweights or hooks 7, 7 up and down. The pulleys 20, 20', at the top endsof the posts, and the pulleys 21, 21 at the tips of the jibs, areprovided in a plural number, so that the weights 7, 7 may be movedhorizontally independently of the vertical movement of thejibs 4, 4'.

The wires or cables of the jib elevating winches 5, 5' extend intointeriors centers of the posts 2, 2' through the pulleys 18, 18' and thepulleys 19, 19' and reach the tips of the jibs 4, 4 over the pulleys 20,20', to swing the jibs 4, 4 up and down. The pulleys 20, 20 at the topends of the respective posts or mast swivel about the posts 2, 2following the movements of the associated jibs 4, 4.

In the present invention constructed as described above, when the singlecranes are operated individually, the twin operation swivel mechanism 11is held inoperative and the clutches for the winding winches 8, 8' andfor the jib elevating winches 5, 5' are disconnected, so that therespective winches may be operated individually. In further detail, thehoisting and lowering of weights 7, 7' are effected by the cables whichare led to the winding winches 8, 8' over the pulleys 21, 21 at the tipend of the jibs, the pulleys 20, 20' at the top ends of the posts, thepulleys 19, 19' within the posts and the pulleys 18, 18' at intermediateportions of the posts. The hoisting and lowering of the jibs 4, 4' areeffected by the cables which are led to the jib elevating winches 5, 5'over pulleys 20, 20', at the top ends of the posts, pulleys 19, 19'within the posts, and pulleys 18, 18' at intermediate portions of theposts. The jibs 4, 4, as shown in FIG. 2, are swiveled about the posts2, 2', thereby to effect loading and unloading of cargoes into and fromthe two hatches 9, 9'.

When the crane is operated as a twin crane, the jibs 4, 4 are positionedin substantially parallel relation as shown in FIG. 3, with the top orouter ends being located at the same level, and clutches 17, 17' areplaced in an engaged position. By so doing, it becomes possible tooperate winding winches 8, 8 and jib elevating winches 5, 5' in positivesynchronism. The hoisting and lowering of weights 7, 7 and jibs 4, 4 areeffected in the same manner as in the case of single operation, but thesingle operation swivel mechanisms 6, 6' are fixed by a brake and all ofthe structure on above common swivel mount or base 1 is rotated aboutmounting base or support 3 by means of twin operation swivel mechanism 11.

Since winding winches 8, 8', jib elevating winches 5, S'and singleoperation swivel mechanisms 6, 6 are all mounted on common swivel mount1, the construction is simple and maintenance can be effectedadvantageously. In addition, the synchronous operation of the singlecranes, which is most important in the twin operation, can be attainedsimply and positively by engaging clutches 17, 17' of winding winches 8,8 and jib elevating winches 5, 5, and there is no need of a synchronousoperation correcting means. Further, since pulleys 20, 20' at the topends of the posts are rotatable about the respective posts 2, 2', thecables from winding winches 8, 8' and jib elevating winches 5, 5 can behandled smoothly. Still further, since inner race 13 of each singleoperation swivel bearing 12 is fixed to the'associated post 2 or 2, theupsetting moment is taken by said post through pulleys 20, 20' at thetop end of the post, so that single operation swivel bearing 12 can besmall in size.

The embodiment of the invention shown in FIG. 5 differs from that shownin FIGS. 1 through 4 only in that the masts 2 and 2' are interconnected,adjacent their upper ends, by a common support for the pulleys 18, 18'and 19, 19'.

In the embodiment of the invention shown in FIGS. 6 and 7, hoisting andlowering of jibs 4, 4' are effected by hydraulic actuators 22, 22',instead of by cables and elevating winches. In this arrangement, thecorrection of synchronism of the jib elevating mechanisms is effected byswitching the respective hydraulic circuits from series connection toparallel connection or vice versa. Tandem-type hydraulic pumps 25, 25,driven from an electric motor 24, are individually connected tohydraulic actuators 22, 22' through separate conduits, with controlvalves 26, 26' and change-over valves 27, 27 being interposed in therespective conduits (see Fig. 7). FIG. 7 shows valves 27, 27' in thestate wherein the single cranes are used individually.

When the single cranes are used for the twin operation, changeovervalves 27, 27 are shifted, whereby fluid from hydraulic pump 25 entersthe hydraulic actuator 22 through control valve 26, and flows fromhydraulic actuator 22 through change-over valve 27 to actuator 22. Thefluid returns through change-over valve 27 and control valve 26 tohydraulic pump 25. Therefore, the hydraulic actuators 22, 22' makeexactly the same stroke. On the other hand, the fluid from the hydraulicpump 25' returns directly to the hydraulic pump 25' through the controlvalve 26'. The hydraulic parts used in this embodiment are all mountedwithin the common swivel mount ll, except for the actuators 22, 22'.

In the above-described embodiment, in which hydraulic actuators are usedas the jib elevating means, when the individual cranes are usedindependently twin operation swivel mechanism independently, is heldinoperative and clutch 17 of winding winches 8, 8' is disengaged withchange-over valves 27, 27' being placed in the positions I in FIG. 7.

The hoisting and lowering of weights 7, 7' are effected by the cablesled to winding winches 8, 8' over pulleys 21, 21' at the top ends of thejibs, pulleys 20, 20' at the top ends of the posts, pulleys 19, 19'within the posts and pulleys l8, 18 at intermediate portions of theposts. Hoisting and lowering of the jibs 4, 4' are effected by thehydraulic actuators 22, 22. Horizontal movement or traverse of jibs 4i,4' is effected by swinging them about the respective posts 2, 2', toload or unload cargoes into or from the two hatches 9, 9'.

On the other hand,when the crane is used as a twin crane, jibs 4, 4 areset in parallel relation, with the top ends thereof located at the samelevel, and then clutch 17 is engaged and change-over valves 27, 27 areshifted to positions II. By so doing, winding winches 8, 8 and jibelevating hydraulic actuators 22, 22 can be operated in positivesynchronism. For swinging the cranes, in this case, single operationswivel mechanisms 6, 6'are fixed by a brake and all of the structure onand above common swivel mount 3 is swiveled about support 3 on the shiphull, by means of the twin operation swivel mechanism 11.

In this embodiment wherein synchronism of the jib elevating mechanism iseffected by switching the hydraulic circuits from series connection toparallel connection or vice versa, the synchronous operation, in the useof the crane as twin crane, can also be achieved simply and positively,by the connection of clutch 17, for the two winding winches 8; 8, andthe shifting of the change-over valves 27, 27','for the jib elevatinghydraulic actuators 22, 22, and there is no need of a synchronousoperation correcting means. In addition, since winding winches 8, 8' andsingle operation swivel mechanisms 6, 6' are mounted on the commonswivel mount, and the twin operation swivel mechanism 11 and the jibelevating power means (the electric motor 24, the hydraulic pumps 25,25', the controlling valves 26, 26 and the change-over valves 27, 27')are also mounted in the common swivel mount 1, the construction issimple and maintenance can be advantageously effected. Furthermore,since actuators 22, 22 are used for the jib elevating mechanism, thereis no fear of jibs 4, 4' dropping due to breakage of cables, and furtherthe jackknife phenomenon (the phenomenon in which a warping force actson the crane in the erected state of the jibs 4, d) can be avoided.

The preceding illustrations and examples are given merely by way ofexample, for clear understanding of the nature of the invention and arenot intended to unduly limit the scope of this invention, the inventionincluding obvious equivalents and modifications to the extent that suchequivalents and modification would be apparent and obvious to the personof skill in this particular art.

What is claimed is:

1. A twintype slewing crane comprising, in combination, a common basemounted for rotation about an upright axis; a pair of relativelyelongated upright masts supported on said base in spaced parallelrelation to each other; respective booms mounted on said masts forswinging movement in their vertical plane and for rotational traverseabout the associated mast, each boom supporting a respective hoistinghook for lifting and lowering loads; individually operable hoistingwinches on said base each connected by a respective cable to arespective hook; individually operable boom elevating mechanisms on saidbase each connected to a respective boom to raise and lower the latter;individually operable drive means on said base each operable to rotate arespective boom about its associated mast; driving means operable torotate said base, together with all of the components mounted thereon,about said upright axis; first coupling means selectively operable tointerconnect said winches for conjoint synchronized operation; andsecond coupling means selectively operable to interconnect saidelevating mechanisms for conjoint synchronized operation; whereby saidbooms and hooks may be operated independently for handling individualloads, or may be operated conjointly as a twin-type crane to hoist acommon relatively heavy load.

2. A twin-type slewing crane, as claimed in claim 1, in which said boomelevating mechanisms comprise individually operable elevating winches onsaid base each connected by a respective cable to a respective boom.

3. A twin-type slewing crane, as claimed in claim 2, in which said firstand second coupling means comprise respective clutches.

4. A twin-type slewing crane, as claimed in claim 3, in which saidhoisting winches are axially aligned with each other and said elevatingwinches are axially aligned with each other.

5. A twin-type slewing crane, as claimed in claim 2, including pulleysmounted internally of each mast; said cables being craned over saidpulleys.

6. A twin-type slewing crane, as claimed in claim 2, including a supportinterconnecting said masts near their upper end; and pulleys on saidsupport; said cables being craned over said pulleys.

7. A twin-type slewing crane, as claimed in claim 1, in which said boomelevating mechanisms comprise individually operable hydraulic actuatorseach connected between a mast and the associated boom; means on saidcommon base providing a supply of hydraulic fluid under pressure;respective lines connecting said lastnamed means to said actuators;respective control valves interposed in each supply line; and respectiveselector valves interposed in said supply lines and selectively operableeither to connect the associated control valve to the respectivehydraulic actuator or to connect both actuators in series with onecontrol valve.

9. A twin-type slewing crane, as claimed in claim 1, including a supportrotatably mounting said common base; said driving means including a ringgear secured to said support and a motor mounted on said common base andhaving an output pinion engaged with said ring gear.

1. A twin-type slewing crane comprising, in combination, a common basemounted for rotation about an upright axis; a pair of relativelyelongated upright masts supported on said base in spaced parallelrelation to each other; respective booms mounted on said masts forswinging movement in their vertical plane and for rotational traverseabout the associated mast, each boom supporting a respective hoistinghook for lifting and lowering loads; individually operable hoistingwinches on said base each connected by a respective cable to arespective hook; individually operable boom elevating mechanisms on saidbase each connected to a respective boom to raise and lower the latter;individually operable drive means on said base each operable to rotate arespective boom about its associated mast; driving means operable torotate said base, together with all of the components mounted thereon,about said upright axis; first coupling means selectively operable tointerconnect said winches for conjoint synchronized operation; andsecond coupling means selectively operable to interconnect saidelevating mechanisms for conjoint synchronized operation; whereby saidbooms and hooks may be operated independently for handling individualloads, or may be operated conjointly as a twin-type crane to hoist acommon relatively heavy load.
 2. A twin-type slewing crane, as claimedin claim 1, in which said boom elevating mechanisms compriseindividually operable elevating winches on said base each connected by arespective cable to a respective boom.
 3. A twin-type slewing crane, asclaimed in claim 2, in which said first and second coupling meanscomprise respective clutches.
 4. A twin-type slewing crane, as claimedin claim 3, in which said hoisting winches are axially aligned with eachother and said elevating winches are axially aligned with each other. 5.A twin-type slewing crane, as claimed in claim 2, including pulleysmounted internally of each mast; said cables being craned over saidpulleys.
 6. A twin-type slewing crane, as claimed in claim 2, includinga support interconnecting said masts near their upper end; and pulleyson said support; said cables being craned over said pulleys.
 7. Atwin-type slewing crane, as claimed in claim 1, in which said boomelevating mechanisms comprise individually operable hydraulic actuatorseach connected between a mast and the associated boom; means on saidcommon base providing a supply of hydraulic fluid under pressure;respective lines connecting said last-named means to said actuators;respective control valves interposed in each supply line; and respectiveselector valves interposed in said supply lines and selectively operableeither to connect the associated control valve to the respectivehydraulic actuator or to connect both actuators in series with onecontrol valve.
 8. A twin-type slewing crane, as claimed in claim 1,including a respective annular bearing embracing each mast adjacent itslower end, the inner race of each bearing being secured to theassociated mast and the outer race of each bearing supporting theassociated boom; each of said drive means being connected to arespective outer bearing race.
 9. A twin-type slewing crane, as claimedin claim 1, including a support rotatably mounting said common base;said driving means including a ring gear secured to said support and amotor mounted on said common base and having an output pinion engagedwith said ring gear.